The purpose of this study is to examine and compare the relative in vitro cell-mediated reactivity of lymphocytes from regional lymph nodes, distant lymph nodes, spleen and peripheral blood of rats bearing spontaneous (chemically induced) as well as transplantable syngeneic oral tumors. Highly purified lymphocytes and tumor cells are being harvested and the degree of cell-mediated reactivity monitored at various stages of tumor progression by the use of a microcytotoxicity assay. In addition to providing a new study model, this analysis may further our knowledge of the importance of the regional lymph node in the immune response to oral neoplasia. This could have direct importance with respect to clinical chemotherapeutic and surgical treatment of oral cancer.